Centrifuge machine



June 15, 1954 R. w. HONEYCHURCH 2,681,180

CENTRIFUGE MACHINE Filed April 10, 1951 2 SheejLs-Sheet l FIE J INVENTOR. @aber/ Wf/anegchurc/i June 1954 R. w. HONEYCHURCH 2,681,180

CENTRIFUGE MACHINE Filed April 10, 1951 2 Sheets-Sheet 2 /4b F 1 E E 470 47c i /5 I E. INVENTOR.

fiaber/ Wfianegc/vurc/v .4 TTOR/VE V5 Patented June 15, 1954 UNITED STATES PATENT OFF-ICE? CENTRIFUGE MACHINE Robert W. Honeychurch, Oakland; Calif.,' assignorto Merco Centrifugal Co.; SanFrancis co, Calif., a corporation of California Application April 10, 1951, Serial No. 220,168

Claims.

This: invention relatesgenerally to centrifuge machines .of the type adapted, for the continuous discharge of centrifugally separated overflow and "underflow fractions.

Centrifuge machines of the above character generally make use of a housing or like structure which surrounds the rotor and which is provided with separate receiving chambers or volutes for receiving the centrifugally separated overflow and underfiow fractions. A partition or likeistructure. serves to separate these chambersrand-is provided. with an opening for accommodating .a part of the rotor. The provisionfor discharging the overflow material generally takes the form of an annular lip from which the overflow material is discharged outwardly into the overflow. receiving chamber or volute... The provision for discharging the centrifugally separated underflow material may be a plurality of underflow nozzles mounted upon the periphery of the rotor and discharging into theunderfiow chamber. Frequently the motor is mounted vertically as disclosed, for example, in .Peltzer et al., 2,013,668 and Merrill et a1., 753,301, filed June '7, 1947, and nowgranted as Patent Number 2,559,453.

With: a machine of the above character a problem is involved in preventing comrningling of the discharged overflow and underflow materials... According to my observations this is due to the high speeds of rotation employed, which develop windage tending to cause vapor and atomized droplets to be drawn from the overflow-into the. underflow chamber. No satisfactory-.means hasbeen developed for preventing such contamination. A close clearance between theabove mentioned partition wall and the a"- jacent portionof the rotor is not practical because of lateral oscillation of the rotor-during operation. Seals of the labyrinth type are com plicated and expensive and are not satisfactory for the same reason, namely, because the clear-- ances between the partition wall and the rotor must. be relatively large to accommodate lateral oscillation.

For many types of services it is quite important to minimize contamination of terial with overflow, particularly when it is ole-- sired to secure relatively sharp separation with the withdrawal of an underflow containing a minimum amount of material present in the overflow. In this connection particular referenceucan be made to centrifugal treatment of starch slurries containing gluten and starch particles, where it is frequently desirable to with-- the underfiow madraw a starch underflow. containinga minimum/a.

amount of gluten.

contamination of the type describedabove;

Another object of theinventionis to provided. a novel. means for forming an effective seal beaig. tween the overflow and under-flowevolutesofalcentrifuge machine, whichxwill .be characterized by mechanical simplicity.

Additional. objects and features of the inveir-e. tion will appear from the following description in which the preferred embodimenthas been set; forth in detail in conjunction with the accomf--..

panying drawing.

Referring to the drawing: Figure 1 invention Figure 2. is a quarter bottomplan view, on anewenlarged scale, showing. the seal ring which is incorporated in the machine of Figure 1-. Figure 3 is a cross-sectional detail taken-on theline 3 3 of Figure. 2.

Figure 4 is a cross-sectional detailtakemon:

theline 4-4 .of Figure 2.

Figure 5 is a cross-sectional detail taken--on the line 5-5 of Figure 2.

is a side elevational view in sections. showing a centrifuge incorporating the present:

construction of these parts can be the same a's disclosed in'said application 753,301; Thus thei' housing is formed to provide an upper overflow volute chamber #2, and a lower underfiowvolutechamber [3. These chambers are separated by the partition-wall id, which-is providedwith an opening 15 ample to accommodate the upper part of the rotor.

drive shaft. l1. (not shown) is the chamber |2,'and removedthrougha suit able pipe (not shown),

The periphery of the rotor is provided witha plurality of 'circumferentially spaced underfi'ow discharge nozzles 2 l,- which discharge underflow material into the volute chamber I3. Such material is removed from chamber 13 through suitable piping (not shown) and the major part is continuously returned back into the centrifuge rotor by way of a return circuit.

A feed chamber 22 is formed in the upper part of the housing. Feed material introduced into the chamber 22 flows downwardly through a passage 23, which is formed by the nested sleeves 24 and 26. This passage delivers material into the space 21 and from thence the material passes outwardly through the annular passage 28 into the separating chamber 29. The chamber 21 is formed within a member 3| which is seated within the rotor and provided with vanes 32 for imparting rotary velocity. A stack of separating discs 33 are mounted on member 3| and act upon material in the main separating chamber.

At the lower end of the housing there is a chamber 34 which is adapted to receive underflow material from a return circuit. Such material discharges upwardly through nozzle 36 and the opening 31 in the lower portion of the rotor. It is deflected laterally by the plate 38 to pass between the circumferentially spaced and incline vanes 39. From thence the material flows through the passages 41 to be finally delivered into the outer peripheral portion of the main separating chamber. The return circuit for the underflow material may be a pipe (not shown) connected between volute l3 and chamber 34, and from which a minor part of the underflow is withdrawn from the machine. In some instances the pipe may include a flotation cell or vent box.

The centrifuge described above is similar to that described in copending Merrill et a1. application Serial No. 753,301, filed June '7, 1947. When in operation material is supplied continuously to the feed chamber 22, a continuous discharge of overflow is established over the lip I9, and a continuous discharge of underflow established through the nozzles 2|. The major part of the underflow material is continuously returned into the centrifuge chamber by way of the nozzle 35, whereby the returned material discharges through the nozzles 2| together with the first centrifugally separated underflow material. Any material spilled from the underflow discharge nozzles, or from the volute chamber I3 is collected in the lower part of the housing, and is merged by aspirating action with the upwardly jetting returned material by virtue of the annular member 52.

Mounted upon the rotor extension l3 there is a seal ring 43 which is preferably constructed as illustrated in Figures 2 to 5, inclusive. The inner periphery of this ring is provided with an annular recess 44 which is seated upon and secured to a flange 46 formed on the rotor extension 18. The lower side of the ring is provided with a plurality of circumferentially spaced vanes 47. These vanes are inclined to radii from the center of the ring (Figure 2), whereby their outer ends lla are in trailing relation to their inner ends 4112, considering the normal direction of rotation. Except for the outer ends 41a, the lower faces ile of the vanes are preferably inclined to the plane of rotation whereby the advancing edge 41d is lowermost. Also it is preferable to taper each vane (Figure 3) in the direction of its length whereby its lower edge is generally parallel to the adjacent face of wall I4.

The seal ring 43 is located with respect to the dimensioning of the partition wall It that the vanes 41' normally overlie the inner peripheral margin hid of the partition (Fgure 3). The

margin [4a is shown provided with an inner raised flange Mb, which has its upper end face in close proximity with the lower face of the seal ring in a zone located inwardly of the vanes 41. The running clearance 49 provided between the flange 14b and the seal ring 43 is sufficient to accommodate normal lateral oscillation of the rotor.

Operation of my machine can be explained as follows: Assuming that a feed is being supplied to the rotor and that the rotor is being driven at a proper speed with continuous discharge of centrifugally separated overflow and underflow fractions, a considerable amount of vapor and mist exists within the housing and particularly in the volute chamber I2 and in the interior of the housing below the partition wall M. This is due to splashing and spraying of the material as it is discharged from the rotor and to windage induced by the high speed of rotation. Without the seal ring 43 there is a tendency for vapor and atomized particles from the volute chamber !2 to be drawn downwardly through the clearance 49 into the main part of the housing. Such material finds its way into the underflow volute chamber 13, to be discharged with the underflow material, and serves to contaminate the underflow as finally withdrawn from the machine. With the seal ring 43 applied to the machine as previously described, an effective seal is formed between the upper part of the rotor and the partition wall I i, and as a result no part of the overflow material can pass downwardly to merge with the underflow.

The eifectiveness of my seal is attributed to the action of the rotating vanes 41, which serve to neutralize tendency toward downward windage through the openings 49 and 15, thus preventing a carry-through of vapor and atomized particles. In the event any overflow particles splash toward the clearance 49, they are repelled by the counterwindage developed by the vanes, or in the event the particles contact the vanes, they are impacted and redischarged into the chamber [2. The net result is that movement of material from the overflow to the underflow volute chamber is totally eliminated and the machine is capable of producing relatively sharp separations.

A particular feature of the invention is that it does not require close'mechanical clearances and is relatively simple in construction compared to more expensive and elaborate seals. Furthermore, the invention is readily adaptable to a wide variety of centrifuge machines, where it is desirable to produce a seal between relatively rotatable parts as previously described.

I claim:

1. In a centrifuge of the type having a rotor adapted to receive a feed material and having provision for the separate discharge of centrifugally separated overflow and underflow fractions, means forming overflow and underflow receiving chambers surrounding said rotor and. serving to receive said fractions, the chambers having a partition wall between the same, the partition wall having an opening to accommodate a portion of the rotor, a seal ring mounted upon the rotor in proximity with the inner margin of said partition wall, and vanes carried by the seal ring and serving to neutralize windage tending to occur through said opening from the overflow to the underflow chamber.

2. A centrifuge as in claim 1 in which said vanes are located adjacent the inner margin of the partition wall in a zone which generally surrounds the opening.

3. A centrifuge as in claim 2 in which said vanes are disposed at an inclination to radii from the center of the ring, with the outer ends of the vanes trailing the inner ends of the same for the normal direction of rotation of the rotor.

4. In a centrifuge of the type having a vertical rotor adapted to receive a feed and having provision for the separate discharge of centriiugally separated overflow and under-flow fractions, means forming overflow and underflow receiving chambers surrounding the rotor and serving to receive said fractions, the chambers being one above the other and having a partition wall between the same, the partition wall having an opening to accommodate a portion of the rotor, the inner margin of the partition wall having a flange formed on the same, a seal ring mounted upon the rotor above said flange and disposed within the overflow chamber, the lower face of said seal ring being spaced from but in proximity with said flange, and a plurality of circumferentially spaced vanes mounted upon the lower face of the seal ring and having a zone of operation surrounding said flange, said vanes being inclined with respect to radii from the center of the ring whereby their outer ends trail their inner ends with respect to the normal direction of rotation of the rotor.

5. In a centrifuge of the type having a rotor adapted to receive a feed material and having provision for the separate discharge of centrifugally separated overflow and underfiow fractions, means forming overflow and underflow receiving chambers surrounding said rotor and serving to receive said fractions, the chambers having a partition wall between the same, the partition wall having an opening in a horizontal plane to accommodate a portion of the rotor, a seal ring mounted upon the rotor in proximity with the inner margin of said partition wall and overlying said wall, and circumferentially spaced vanes carried by the seal ring and depending from its lower side toward said margin, said vanes serving to neutralize windage tending to occur through said opening from the overflow to the underfiow chambers.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,149,578 Hall Aug. 10, 1915 1,715,597 Haug June 4, 1929 2,092,484 Tomlinson Sept. 7, 1937 2,145,541 Forsberg Jan. 31, 1939 2,525,629 Zimmerman Oct. 10, 1950 

